Utter rubbish. Access to the window motors is simply a matter of removing 4 screws and some pulling on the door trim. Nothing will be destroyed in the process and IF they do any damage, it could only be some plastic studs (hence no significant costs).
Watch out for that dealer, is my guess! They might bill for unnecessary things.
Just FYI, to read about removing the trim, read my small 'guide' here. There's also a link to some pictures of the inside of your door. The large black thing in the center of the door is the window motor.
http://www.a2forum.net/forum/topic.asp?TOPIC_ID=3129
And as for your problems: I find it hard to believe that both window motors would burn out together.
Do they make any sound at all? Do they try to work? If not, it might simply be a fuse. Check the manual to see which one it might be.
And as for central door locking: those motors are somewhat more burried inside the door, but still accessible. Especially for a dealer.
I'd say they should be able to diagnose the problem quite fast and then either blame the motors, or blame the Control Unit. And of course, the latter is expensive...
Good luck,
Edo
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(2003 Silver 1.4 Tdi Exclusive(SE), 95bhp/235Nm chiptuned by ABT, black interior, sport seats, heated mirrors, JVC KD-SH909RB cd-receiver, Infinity Kappa 63.1 + Vifa on-dash tweeters, 12" Subwoofer on 300w Amp)